Carbon black-rubber masterbatch production



April 1l, 1961 R. s. HANMER CARBON BLACK-RUBBER MASTERBATCH PRODUCTION Filed Deo. 26, 1956 ww-mo Y INVENTOR. R.S. HANMER ATTORNEYS wmmUXm im? om 555m 586mm i.

United States cARnoN BLACK-RUBBER Masrnnnarcn PRODUCTION Robert-S; Hanauer, Bartlesville,- Okla., assiguor 1to-Pl1illips-r Petroleum Company, a corporation of Delaware Filed Dec. 26, 1956, Ser. No. 630,551.

5 Claims. (Cl. 260-41.5)

This invention relates to carbon black-rubber masterbatch production. ln a-furtherfaspect this invention relates to carbon-black rubber masterbatch productionbatches in that a considerable amount of the productis;

lostas'eiines during its production Usual operation involves separating the coagulumfrom the serum, which maybe reurnedr-to the coagulation zone, and then to wash f arent thev coagulum with water, separate the water from the\ coagulum and further process the coagulum. Fines. are, lost:l in the serum and in the water from the subsequent washing operation. Losses of lines in the serum are small since this stream is usually returned to the coagulation zone except for the small portion which is discarded asiexcess;

The' following are objects of my invention.

An object ofl my invention is to provide an improvedV process for the production of carbon black-rubber `masterbatcli; A further object of my invention is to provide a processfor the production of this masterbatch whereinlosses due to lines are minimized. A further object of my invention is-to provide apparatus for preparing carbon black-rubber masterbatch wherein losses due to nes are minimized.

Other objects and advantagesof my invention will be apparent to one skilled in the art upon reading this application.

Accompanying and forming a part of this specification isv adrawing showing, partly schematically, the process: and apparatus of my invention.

A` wellknown practice in the rubber industry is to prepare rubber-carbon black masterbatchesy by a latex masterbatchingl operation, i.e., a carbon black slurry is blended Iwith a'rubber latex and the mixture is coagulated; Anexte'nder oil can also be added, if desired, andthe mixture coagulated to give a rubber-carbon black-extender oil composition. In the usual procedure, themixture ofA rubber latex and carbon black is iirst passed to a coagulation tank where a coagulant such as brine-acidLis added andit is th'en/ transferred to a soap conversion` zone-where suiiicient time is allowed for conversion of the soaptoacidf.' Gbviously, other coagulation systems can' be used. The mixture is transferred to a shaker. screen where" rubber crumb containing carbon black is separated from the serum. The serum which contains some lines,A excess acid; and salt, is usually recycled to tlie acid-salt make-up stream to the coagulation tank. An outlet' is provided in the recycle line for bleeding 0E excess liquidl Rubber crumb from the shaker screen is passed to a zone where it is water Washed.

ofthe crumb from the wash Water and thence to further It is then transferred to another shaker screen to eiect separation,`

while the wash' water containing lines is discharged as.,

waste. i

A much=1argerpercentage ofl lines results from the washing operationthanfromtheiirst separation of-rubberI crumb tromserumand considerable losses result when no provision.is.;made.for recovery-of thev fines.- Filtra- `tion of the washedcrumbis ,ditiiculton account of` the tendency ot the. very/.line particles to clogthe shaker screen-whichgis. constructed ofthe nest mesh material that*ispracticablerincrder to minimize' the fines losses.

Llravediscoveredvthatif the rubber crumb containing r carbon black is: transferredffrom. the shaker screen to ia perforated-rolling beltandthe serum orwashwater is lsprayed or otherwisemade. toy flow'evenly, over the layerz of-crumbon. the.belt,.there; is a substantial reduction in. fines-losses: Therubber crumb provides a continuously.

that a larger quantity ofV line particle size rubber will.

passthrough. acoarser screen=is.of little consequence -as it`will be retainedby the crumb on the roller belt; as the serumis sprayed over it. Whereas screens of approxif mately. 1.00, mesh-,.say. fto 150 mesh have beencon- Sider-ed. necessary,vthe. use of my invention permitsuse ofscreensin the. range of 40 to 80 mesh.

My invention ,can probably be best understood by referenceto.theaccompanying drawing. In this drawing the principal pieces-of: apparatus used in carrying. ont my, invention comprise a Vcoagulation tank 11, a soap conversion tank. 12,.a first shaker screen 13, a first perforated conveyor. belt- 1.4, a water wash tank- 16, a second shaker'. screenl, a secondfperforatedconveyor belt 18', a hammer. mill.. 19,- and` a. dryer Z1.

said coagulation tank. Coagulant4 is. supplied throughV conduitl 23. Theeluent from coagulation tank. 11 is passed to soap coi'iversionY tank 12. by means of. conduit 24. Fromsoap conversiontank 12 the mixture ofV carbonr black-rubber crumb and liquid is passed to shaker screen 13 by means ofconduit26. The shaker screen is powered by. motor 27. Solid material conduit 23 is providedfor conveying material from rst shaker 13 to perforated conveyor belt 14 and conduit 29 is providedto convey solid material from first shaker 13 to water Wash tank 16. Spray means 31, 32, 33, and 34 are provided adjacent the upstream end of perforated conveyorbelt 14. Liquid passing through perforated conveyor belt 14 is collected in tank 36 which is provided' with outlet conduit 37, this conduit extending to and communicating with coagulant supply conduit 23. A liquid removal conduit 33 having pump 39 therein extends fromr the lower portion ofshaker 13. Conduit 41 extends from the downstream end of conduit 38 to spray means 31 through 34, previously described. Conduit tlf.y connects conduit 38 with conduit 37. Extending from the bottom of wash tank16 there is provided conduit 43 which communicates with and'. extends to the upstream end portion of second shaker screen 17. Shaker screen 17 is powered by motor 44. Extending fromshaker screen 17 is conduit 46, this conduit conveying solid material to the upstream end of perforated conveyor belt 18. Conveyor belt 18 is provided with spray means 47, 4S, 49, and 51. Extendingy from the lower end portion of shakerv screen 17 is liquid conduit 52, having pumpc53 therein, conduit Patented. Apr. 1.1 1,961.-

l Coagulation tanlc11'` is. provided with inlet conduit 22-y by means ofwhich. a. mixture of latex and carbonv black slurry is suppliedv to.

S2 extending to spray means 47 through 51. Liquid passing through perforated conveyor belt 18 is collected in tank 54 and conveyed to waste by means of conduit 56.

Hammer mill 19 is provided at the downstream end of perforated conveyor belt 18. Solid material from hammer mill 19 is conveyed to dryer 21 by means of conduit 57 and the product from dryer 21 is recovered at line 58.

From this drawing the operation of my improved process should be evident. slurry are coagulated in coagulation tank 11 by conventional means and passed to soap conversion tank 12 wherein the soap is converted to the acid. The coagulum is passed to shaker screen 13 wherein it is separated from the serum. At this point, alternative processes are possible within the scope of my invention. In one method, the crumb is passed directly to Wash tank 16 by means of conduit 29 and the serum is passed by means of conduits 38, 42, and 37 to the coagulation tank 11. A portion of the serum is discarded through conduit 59. Following washing of the coagulum with water, the water and crumb is passed to shaker screen 17 by means of conduit 43. Coagulum is passed from shaker screen 17 to perforated conveyor belt 18 by means of conduit 46, being distributed on the conveyor belt by suitable means. The separated wash water containing a considerable amount of fines is passed by means of conduit 52 to spray means 47, 48, 49, and 51. This liquid containing the nes is sprayed upon the layer of rubber crumb and the major amount of the fines are deposited upon and stick to the rubber crumb. The wash water, substantially free of fines, passes through the belt and collected in tank 54 from which it is passed to waste or other use through conduit S6. The crumb continues to pass along the perforated conveyor belt 18 and drains to a moisture content preferably not above 30 or 40 weight percent water. The crumb passes from the downstream end of conveyor belt 18 to hammer mill 19 wherein it is disintegrated. It is passed to dryer 21 by means of conduit 57 wherein a product of the desired moisture content is produced.

Alternatively, the crumb from shaker screen 13 can be distributed upon perforated conveyor belt 14 by means of supply conduit 2S. In this modification the serum recovered from shaker screen 13 is passed by means of conduits 38 and 41 to liquid spray means 31, 32, 33, and 34. Substantially all of the fines in this serum are deposited upon the rubber crumb on perforated conveyor belt 14. The serum is collected in tank 36 and passes by means of conduit 37 to the coagulation tank 11, a small portion of this recycle serum being discarded through conduit 59.

From the downstream end of perforated conveyor belt 14 the rubber crumb passes to water wash tank 16. In this modification it is also desirable to have a belt of suicient length so that a considerable portion of the serum drains from the rubber crumb prior to its introduction into wash tank 16, this reducing the amount of wash Water required.

' The second modification just described provides 4the additional advantage in that nes are removed from the recycle serum and the fines are not lost in the small portion of material which is discarded. However, since the amount discarded is small, the additional equipment required for this modification is sometimes considered unnecessary. Obviously, fines recycled to the coagulation tank are not lost.

The following specific example is given as illustrative of the manner of carrying out the present invention and demonstrates the specific improvement obtained thereby. However, it should be understood that our invention is not limited to this specific example.

Example Butadiene and styrene are copolymerized in aqueous The mixture of latex and black lemulson at 41 F. in accordance with the following recipe:

Parts by weight 72 Butadiene Styrene 28 Water Rosin soap, K salt 4.5 KOH 0.1 KCl 0.4 Tarnol N1 0.1 Sequestrene AA2 0.02 FeSO47H2O 0.01 NaSOgCHzOI-I-ZHgO3 0.05 p-Menthane hydroperoxide 0.05 Tert-dodccyl mercaptan 0.23

Parts by weight Carbon black 50 Marasperse1 2 NaOH 0.2 Water 240 1 Sodium liguin sulfonate.

The carbon black slurry is blended with the rubber latex in proportions such that 50 parts by weight of carbon black is employed per'l00 parts rubber. This latex masterbatch is fed to the coagulation tank where brine and acid are added and thence to the soap conversion zone where conversion of the soap to acid occurs. The material is passed from the soap conversion zone to a shaker screen where the serum is separated from the rubber crumb containing carbon black. Serum is recycled to the brine-acid make-up line. Provision is made in the recycle line for withdrawal of excess liquid as necessary. Rubber crumb from the shaker screen is transferred to a Washing tank where it is washed with water, passed to another shaker screen, and then to a perforated roller belt. A layer of rubber crumb is formed on the belt. The wash water or serum is pumped through a transfer line to spray nozzles where it is spread evenly over the surface of the rubber crumb. The crumb drains to a moisture content of not over 30 to 40 weight percent water and is then passed to a hammer mill and finally to a drier. The loss of rubber as lines is only 1.1 weight percent when operating in this manner.

When the run is repeated without provision for recovery of fines from the wash water from the second shaker screen, the loss of rubber as nes is 4.6 weight percent.

The emulsiiiers which can be used include not only the soaps such as alkali metal or ammonium stearates, oleates, rosnates, and the like, but also alkali metal aralkyl sulfonates, aryl sulfonate's, sodium lignin sulfonates, mercaptan ethylene oxide condensation products, phenol ethylene oxide condensation products, etc. Mixtures of emulsiers are frequently used. As the emulsier or mixture thereof is varied, it will, in some instances, be necessary to vary the coagulation system. For instance, alcohols are used as coagulation agents in some cases.

As many possible embodiments may be made from my invention without departing from the scope thereof, it is to be understood that all matter herein set forth is to be interpreted as illustrative and not as unduly limiting the invention.

claim:

l. In the process of producing carbon black-rubber masterbatch wherein a latex-carbon black slurry is coagulated to form a crumb, the improvement comprising passing liquid separated from the crumb and containing fines through a mass of the crumb thereby removing said nes from said liquid. s

2. The process of reducing loss of ines in the production of carbon black-rubber crumb, comprising mixing rubber latex with a carbon black slurry; coagulating solids in the resulting mixture; removing the resulting crumb from the serum; washing said crumb with water; separating wash water from said crumb, said wash water containing fines; and passing said wash water containing flnes through said crumb, said crumb Serving to remove fines from said wash Water.

3. The process of reducing loss of lines in the production of carbon black-rubber crumb, comprising mixing rubber latex with a slurry of carbon black in water; coagulating solids in the resulting mixture in a coagulation zone; removing the resulting crumb from the serum; returning at least the major portion of the serum to the coagulation zone; washing said crumb with Water; separating Wash water from said crumb, said wash water containing fines; forming a layer of said crumb; spraying said wash water containing fines onto said layer of crumb, said layer of crumb serving to remove iines from said wash water; draining suicient wash water from said crumb to provide a crumb containing not more than 40 weight percent moisture; disintegrating said drained crumb, passing resulting disintegrated crumb to a drying zone; and recovering resultingy dry carbon black-rubber crumb.

4. The process of preparing dry carbon black-rubber l crumb comprising mixing rubber latex containing a soap emulsier with a slurry of carbon black in water; coagulating solids in the resulting mixture by adding an aqueous solution of brine and acid in a coagulation zone and holding the mixture in a soap conversion zone until coagulation is complete; removing serum from the resulting crumb, said serum containing lines; forming a layer of said crumb; spraying removed serum containing fines on said layer, said layer of crumb serving to remove nes from said serum; returning at least the major portion of said serum to said coagulation zone; washing said crumb with water; separating wash water from said crumb, said wash water containing lines; forming a layer of said crumb; spraying said wash water containing lines onto said layer of crumb, said layer of crumb serving to remove fines from said wash water; straining suicient wash Water from said crumb to provide a crumb containing not more than weight percent moisture, breaking up said drained crumb; drying the crumb following said breaking up; and recovering resulting dry carbon blackrubber crumb.

5. In the process of producing carbon black-rubber masterbatch wherein a slurry of carbon black and a butadiene-styrene copolymer is coagulated to form a crumb, the improvement comprising passing liquid separated from the crumb and containing lines through a mass of the crumb, thereby removing said iines from said liquid.

References Cited in the lile of this patent UNITED STATES PATENTS 2,218,836 Von Kohorn zu Hornegg Oct. 22, 1940 2,509,664 Amon et al. May 30, 1950 2,640,042 Howland et al. May 26, 1953 2,767,065 Hoggatt et al. Oct. 16, 1956 

1. IN THE PROCESS OF PRODUCING CARBON BLACK-RUBBER MASTERBATCH WHEREIN A LATEX-CARBON BLACK SLURRY IS COAGULATED TO FORM A CRUMB, THE IMPROVEMENT COMPRISING PASSING LIQUID SEPARATED FROM THE CRUMB AND CONTAINING FINES THROUGH A MASS OF THE CRUMB THEREBY REMOVING SAID FINES FROM SAID LIQUID. 